Structure And Spin-orbit Coupling For Diatomic Molecules Cation Containing Metal: SrH~+/SrCl~+ And AlCl~+/AlBr

Metal diatomic molecules are widely found in interstellar space,and their spectroscopy plays an important role in the fields of astronomy and astrophysics.It is also a candidate molecule for laser cooling molecules.Therefore,spectroscopy of metal diatomic molecular ion has important practical value and theoretical significance.In this paper,metal diatomic ion SrH⁺,SrCl⁺,AlCl⁺ and AlBr⁺ were chosen as the research targets.The electronic states structures,spectrum information and transition properties are calculated by using the internally constriction multireference configuration interaction?ic MRCI?method and the Davidson correction?+Q?.The main contents are as follows:?1?Ab initio calculations on low-lying electronic states of strontium hydride cations,SrH⁺,have been performed.The potential energy curves?PECs?of a total of 12?43?-S states,as well as the 23 W states generated from the?43?-S states after considering the SOC effect,have been calculated.The spectroscopic constants and transition properties have been obtained based on the calculated PECs.It indicates that the SOC effect plays a non-negligible role in electronic states of SrH⁺.The potential energy curves,the spectroscopic constants,the dipole moment and the transition dipole moments of SrCl⁺ are also calculated.Our study should shed light on the structure and behavior of low-lying electronic states and should pave further experimental studies on the spectroscopy of strontium hydride cations.?2?The potential energy curves of?43?-S states of AlCl⁺ and AlBr⁺ are calculated,where the spin-orbit coupling effect are first taken into account in calculations.The potential energy curves and spectroscopic parameters of of?43?-S and W states are evaluated.The influence of the spin-orbit coupling effect on the electronic structure of electronic state is analyzed.The perturbation to the vibrational states of C2?47?states is analyzed.The perturbation to the vibrational states C2?47?states is analyzed via the values of the spin-orbit coupling matrix near the avoided crossing points,illuminating the effect of spin-orbit coupling on the spectral intensity and radiative lifetimes.?3?We have performed a theoretical study on the stability and isomerization reactions of C₆H₅⁺ isomers at density functional theory B3LYP/6-311G?d,p?level.We have obtained a total of 60 isomers of C₆H₅⁺ cations,most of which are reported for the first time.The geometries,vibrational frequencies,thermodynamic properties and stability of 28 out of 60 isomers have been summarized in detail.Different ringto-ring and ring-to-chain isomerization pathways,which are connected via 28 transition states,have been investigated using the intrinsic reaction coordinate method.The results show that the isomerization reactions occur via hydrogen migration followed by bond-breaking and reconstruction.